Chemical Reactivity of LSF-(SDC/GDC)-YSZ for Solid Oxide Fuel Cells

摘要

Interfacial reaction between yttria stabilised zirconia (YSZ) and cathode components have been studied under processing conditions compatible with metal support SOFC technology. La_(0.6)Sr_(0.4)FeO3 (LSF40) perovskite has been chosen as cathode material and samarium doped ceria (SDC) or gadolinium doped ceria (GDC) as barrier layer materials, to prevent reaction of the cathode with the electrolyte. Several chemical processes, occur between cathode and barrier layer and between barrier layer and electrolyte. Detailed X-ray diffraction patterns (XRD) were analysed in order to evaluate the reactions between LSF40, YSZ and SDC/GDC materials. Impedance spectroscopy measurements were carried out on symmetrical electrolyte supported cells in order to study the effect of the barrier layer and processing temperature in cell performance. It is found that performance is best when cathode processing temperatures are relatively low, probably due to several interactions between ceria layer and cathode, and ceria layer and electrolyte. The formation of additional intermediate compositional gradient phases in the YSZ-Ceria reaction interface is observed by X-ray diffraction, more over, diffraction peak shifts are observed for mixtures of LSF and SDC/GDC, indicating the existence of cation diffusion among these phases.